The present invention relates to an ink-jet print apparatus and method which print an image on a recording medium by discharging an ink thereon while scanning an ink-jet head relative to the recording medium.
With recent advances in personal computers, especially portable personal computers, the demand tends to arise for liquid crystal displays, especially color liquid crystal displays. However, in order to further popularize the use of liquid crystal displays, a reduction in cost must be achieved. Especially, it is required to reduce the cost of a color filter which occupies a large proportion of the total cost. Various methods have been tried to satisfy the required characteristics of color filters while meeting the above requirements. However, any method capable of satisfying all the requirements has not been established. The respective methods will be described below.
The first method is a pigment dispersion method. In this method, a pigment-dispersed photosensitive resin layer is formed on a substrate and patterned into a single-color pattern. This process is repeated three times to obtain R, G, and B color filter layers.
The second method is a dyeing method. In the dyeing method, a water-soluble polymer material as a dyeable material is applied onto a glass substrate, and the coating is patterned into a desired shape by a photolithographic process. The obtained pattern is dipped in a dye bath to obtain a colored pattern. This process is repeated three times to form R, G, and B color filter layers.
The third method is an electrodeposition method.
In this method, a transparent electrode is patterned on a substrate, and the resultant structure is dipped in an electrodeposition coating fluid containing a pigment, a resin, an electrolyte, and the like to be colored in the first color by electrodeposition. This process is repeated three times to form R, G, and B color filter layers. Thereafter, the resin is thermoset to form colored layers.
The fourth method is a print method. In this method, a pigment is dispersed in a thermosetting resin, a print operation is performed three times to form R, G. and B coatings separately, and the resins are thermoset, thereby forming colored layers. In either of the above methods, a protective layer is generally formed on the colored layers.
The point common to these methods is that the same process must be repeated three times to obtain layers colored in three colors, i.e., R, G, and B. This causes an increase in cost. In addition, as the number of processes increases, the yield decreases. In the electrodeposition method, limitations are imposed on pattern shapes which can be formed. For this reason, with the existing techniques, it is difficult to apply this method to TFTs. In the print method, a pattern with a fine pitch is difficult to form because of poor resolution and poor evenness.
In order to eliminate these drawbacks, methods of manufacturing color filters by an ink-jet system are disclosed in Japanese Patent Laid-Open Nos. 59-75205, 63-235901, 63-294503, and 1-217320.
In general, when a color filter is to be manufactured by using such an ink-jet system, an elongated ink-jet head having a plurality of discharging nozzles is scanned relative to a color filter substrate so as to color a plurality of pixel arrays of the color filter. In this case, since color filters differ in their display areas and pixel pitches, the pitch of the discharging nozzles of the ink-jet head does not necessarily coincide with the pitch of the pixel arrays of a color filter to be manufactured. For this reason, the elongated ink-jet head is inclined at a predetermined angle with respect to the scanning direction to match the pitch of every plurality of nozzles with the pitch of the pixel arrays of the color filter. In this case, it costs much to design an ink-jet head while changing its nozzle pitch. For this reason, an ink-jet head having only one nozzle pitch is used. In this method, to cope with different pixel pitches, the inclination angle of the ink-jet head with respect to the scanning direction is generally changed. Conventionally, the inclination angle of such an ink-jet head with respect to the scanning direction is designed in accordance with the pixel pitch of a color filter to be manufactured and is fixed. When, therefore, color filters with different pixel pitches are to be manufactured, the inclination angle of the ink-jet head is changed. For this reason, a plurality of types of mounting portions must be prepared for the scanning mechanism of the ink-jet head. It takes much labor and cost to design and manufacture a plurality of types of mounting portions for the ink-jet head in accordance with the types of color filters to be manufactured.
In addition, in a color filter manufacturing apparatus using an ink-jet head, to restore the ink-jet head from the clogging state or the like to the normal state, a restoring mechanism for sucking/restoring the nozzles of the ink-jet head is often used. The angle of this suction mechanism must be set in accordance with the inclination of the ink-jet head. Conventionally, the angle of this restoring mechanism is set in accordance with the pixel pitch of a color filter to be manufactured. When, therefore, color filters with different pixel pitches are to be manufactured, the angle of the restoring mechanism must be changed.